I have a similar story Melody… I bought a white linen jacket from Marks… anyway first time I wore it I went shopping and was in TKMax, as I left the store all the alarms went off and I was apprehended by one of their security people… anyway after being taken back into the store (very embarrassing) it was established my jacket from Marks still had a security tag on it and had set the alarms off. I told them it was the first time I had worn it and luckily I still had the receipt, I had more shopping to do but whatever shop I went into all the alarms went off :D
I ended up having to abort the trip and go to the nearest Marks 7 miles away to have the tag removed….. what did marks say?… nothing really only… oh yes it happens sometimes!!! GGGRRRRR